The spectrum of vertical gaze palsy following unilateral brainstem stroke.

A single unilateral lesion, near the midline, may interrupt the pathways involved in vertical gaze just before and after they decussate, inducing an anatomically unilateral, but functionally bilateral, lesion. We report 11 patients with supranuclear vertical gaze palsies (two with conjugate upgaze palsy, four with combined up- and downgaze palsies, two with monocular elevation palsy, and three with vertical "one-and-a-half" syndrome) due to unilateral midbrain strokes.